This is the only thing that has disappointed me with my S3. I wish there was a battery pack that could wirelessly discharge .

There is (or is supposed to be anyway) a wireless charging kit for the S3.

Not sure if it's available, either widely or via eBay or whether it disappeared into the black hole of official Samsung accessories.

I couldn't find anywhere in the UK to buy it. I'm not importing from the states.

here we go...
http://www.mobilefun.co.uk/samsung-g...kit-p37396.htm

Sadly that doesn't surprise me.
There's a lot of accessories Samsung announce that don't make it to the UK (or anywhere).

They seem to be getting better and there have been internal re-shufflings that should specifically improve supply to the UK but I'd expect that to only affect future handsets.